Smoking tobacco composition

ABSTRACT

This invention is for a new smoking composition having improved burning characteristics and comprises tobacco, an ammonium polyphosphate of high molecular weight and a natural or synthetic gum binder. The average molecular weight of the polyphosphate is between about 20,000 and 1,500,000 and the tobacco constitutes about 60-95 percent of the composition.

Elite mi States Patent [191 Monte, deceased [451 Jan. 1,1974

1 1 SMOKING TOBACCO COMPOSITION [21] App1.No.: 143,193

[52] 11.5. CI ..131/l7, 131/140 C, 131/2 [51] Int. Cl. A24b 03/14, A24b 15/00 [58] Field ofSearch.....131/10.1l0.9, 2,17, 4,140;

[56] References Cited UNITED STATES PATENTS 3,459,195 8/1969 Silberman 131/17 R 1,879,128 9/1932 Desper 131/15 A 3.364.935 l/l968 Moshy et al 131/140 P 3,528,434 9/1970 Halter et al. 131/140 P OTHER PUBLICATIONS Kirk -Othmer (Text) Encyclopedia of Chemical Technology Vol. 15, 1969, John Wiley & Son, New York, N.Y., page 274.

Primary Examiner-Melvin D. Rein Attorney-George W. Price et a1.

57 ABSTRACT This invention is for a new smoking composition having improved burning characteristics and comprises tobacco, an ammonium polyphosphate of high molecular weight and a natural or synthetic gum binder, The average molecular weight of the polyphosphate is between about 20,000 and 1,500,000 and the tobacco constitutes about 60-95 percent of the composition.

2 Claims, N0 Drawings 1 SMOKING TOBACCO COMPOSITION This invention relates to new compositions of matter. More particularly, the invention relates to improved compositions comprising tobacco, reconstituted tobacco or tobacco substitutes having improved properties.

in the manufacture of compositions of tobacco, reconstituted tobacco and tobacco substitutes, and particularly in the latter two, various constituents are incorporated in the compositions to improve their qualities in regard to their various properties. One particular problem encountered with such products is their com bustibility. For example, some products of this nature tend to burn too rapidly. This is undesirable when they are transformed into smokeable items. In order to overcome the disadvantages of rapid combustion, numerous constituents have been incorporated into smokeable products made from tobacco, reconstituted tobacco and tobacco substitutes to improve their burn characteristics while not affecting their taste or odor.

Among the materials employed heretofore to change the burn characteristics of these products are ammonium orthophosphate, diammonium acid phosphate and ammonium dihydrogen phosphate, that is, the mono-, di and tribasic phosphates. Although these materials generally act as burn retardants and therefore impart some improvement in burning characteristics to compositions of tobacco, reconstituted tobacco and tobacco substitutes containing them, they produce a black ash of very poor cohesive properties, especially in reconstituted tobacco and tobacco substitute products. Consequently, there existsa need for even greater improvement in the burning characteristics, as well as the other characteristics, such as improved ash appearance and cohesiveness, of these combustible materials as they are consumed. The present invention provides compositions which overcome the disadvantages of the materials mentioned above.

More specifically, the present invention provides a composition comprising tobacco, reconstituted tobacco or tobacco substitutes and high-molecular weight ammonium polyphosphate. Surprisingly, highmolecular weight ammonium polyphosphate not only provides better burn characteristics but also results in the production of a light colored, cohesive ash when the products are consumed bycombustion.

The term tobacco as employed throughout this Specification is used generically and is to be understood to include tobacco in all its forms, that is, such as leaves and stems, as taken from the field, and reconstituted tobacco, and which may be further processed to varying physical shapes, such as sheets, rods, plugs, blocks, shreds and the like or converted into other suitable forms for use as smokeable products such as cigars, cigarettes, pipe plugs and the like.

The term reconstituted tobacco as employed in this Specification is to be understood to mean tobacco in which the leaves or stems have been comminuted to a fine or dust-like particulate condition or refined to a pulp and which may or may not be chemically treated and which may or may not be mixed with a binder or adhesive and subsequently cast into sheets from a slurry which is preferably, although not necessarily, aqueous and in which the sheets are later shredded, cut or otherwise manipulated in order to form smokeable products therefrom. Generally, as mentioned hereinbefore, such tobacco compositions are converted into aqueous slurries and may also contain humectants, flavors and other additives, such as foaming agents, if desirable.

The term tobacco substitutes, as employed throughout this Specification, is to be understood to mean any combustible material, natural or synthetic, which may be used in place of tobacco, such as, but not limited to, naturally occurring nicotine-free plant materials, such as com silk, peat, alfalfa, etc., and partially oxidized cellulosic materials capable of substantially complete oxidation when subjected to combustion. Such partially oxidized cellulosic materials include, but are not limited to, the celluloses and substituted celluloses mentioned hereinbelow in partially oxidized states. When natural occurring plant derivatives are employed in a composition of this invention, they may be utilized in the same manner as natural tobacco. On the other hand, where a partially oxidized cellulosic material is employed, it may be mechanically and chemically manipulated as desirable in order to provide a final product having a suitable shape such as a plug, rod, sheet or the like. In this connection, it is to be noted that such cellulosic materials may be converted to pulps or slurries in a manner known in the art and then combined with the high molecular weight ammonium polyphosphate.

A composition according to the invention can vary widely in proportions of constituents present therein. Usually, the tobacco, reconstituted tobacco or tobacco substitute is present in a major amount along with at least enough, that is, a minor amount of ammonium polyphosphate to impart improved properties .to a smokeable product made therefrom. Generally, as a practical matter, however, a composition in accordance with the invention, whether it contains tobacco, reconstituted tobaccos, or tobacco substitutes, comprises by weight based on the total weight of the composition, on a dry basis, from about 50 percent or less to about 98 percent or more of the tobacco or tobaccolike constituents, the remaining portion of the formulation necessary to make 100 percent in the composition comprising from about 2 percent to about 10 percent by weight and preferably from about 4 percent to 8 percent by weight of high molecular weight ammonium polyphosphate, the optional materials such as humectants, flavors and the like providing the remainder of the composition.

On the other hand, a reconstituted tobacco product or composition in accordance with the invention contains generally from about 50 percent or less to about 95 percent or more by weight, based on the total weight of the composition, on a dry basis, of tobacco in comminuted form and the remaining portions of the formulation include binder, humectant, flavors and other adhesives, with the ammonium polyphosphate mentioned being employed in the same weight amounts indicated above. It is to be understood, that the materials, as mentioned before, may be utilized in the form of aqueous slurries which as a practical matter contain as much water as necessary to make a slurry which can be easily and conveniently handled. Generally, slurries containing about to percent water or other suitable low viscosity vehicle, the remaining portion of the slurry being the tobacco, binder, ammonium'polyphosphate and other constituents are suitable. Such is also the case in regard to those formulations or compositions in which tobacco substitutes are utilized. However, mixtures containing 50 percent or less water or other vehicles may also be converted into suitable shaped articles by plastic extrusion methods.

The high molecular weight ammonium polyphosphates employed in the practice of this invention are white, free-flowing powders containing about 32 percent phosphorous. They have relatively low solubility in water which ranges from about 10 percent to l5 percent at 25 C. On the other hand, boiling can destroy the unique crystal structure of these products which results in essentially 100 percent solubility. The ammonium polyphosphates employed in the practice of the invention have a pH of about 5.8 in a percent aqueous slurry.

The molecular weight (MW) of ammonium polyphosphate suitable for practice in the present invention is in a range of from about 20,000 or less to as high as about 1,500,000 or more as determined by light scattering techniques. A particularly useful ammonium polyphosphate has an average molecular weight of about 200,000. In general, the ammonium polyphosphates used in the practice of this invention lose ammonia gradually at about 215 C. and decompose to form phosphoric acid at temperatures in a range of from 325 to 400 C. Upon decomposition of yield of about 86 percent to 87 percent of the decomposition product is phosphoric acid In addition, ammonium polyphosphates suitable for use in the present invention have a specific gravity of about l.79 and a refractive index of 1.484. The ammonium polyphosphates are available commercially and a particularly useful material is PHOS-CHEK P/30.

In accordance with the invention, a composition which contains a binder can'be prepared with a wide variety of hydrophilic gums which may be derived from either natural or synthetic sources. The naturally occurring hydrophilic gums include the broad carbohydrate and protein classes. The carbohydrate gums comprise gums from animals, plants and microbial sources. The animal sources include glycogen, partially deacetylated chitin and the like. The plant gums and derivatives thereof include cellulose ethers, cellulose esters, starches, starch ethers, starch esters, amylose, amylopectin and ester and ether derivatives of these materials. Further included among the plant gums and derivatives thereof are locust bean gum, guar gum, gum arabic and related seed gums and plant exudate gums. The plant gums further include marine plant gums such as the algins, carageenans, Iaminarins and agar. The microbial gums include the dextrans, phosphomannans, such as described by the U.S. Department of Agriculture under N0. B-l459, B 1428 and the glucuronic acid containing microbial gums, such as described in the U.S. Department of Agriculture under N0. Y-I409. The synthetic hydrophilic colloids which are suitable for use as binders in the compositions of the present invention include polyvinyl alcohol, polyoxethylene and polyacrylamide.

Preferred binders which are particularly useful in carrying out the preparation of compositions in accordance with the present invention include the substituted cellulosic gums. Generally, the substituent groups are lower alkyl and mixed lower alkyl radicals and particularly the lower alkoxy and hydroxyalkoxy substituent groups containing about one to four carbon atoms. Generally, this group of substituted celluloses exhibit the property of thermal gelation. Consequently, water solutions of such thermogelling gums will gel on heating to their specific thermal gelation temperature. Included in the category of such thermogelling gums are methyl cellulose, hydroxypropyl cellulose and its thermogelling derivatives and methylhydroxyethyl cellulose, as well as ethylhydroxyethyl cellulose and ethylhydroxpropyl cellulose. It is to be understood that the substituents present on the cellulose molecule may be any suitable combination of lower alkyl groups, alkoxy groups and hydroxyalkyl groups, so long as the thermogelling properties are retained. Particularly useful materials of this type include high viscosity cellulosic derivatives wherein the viscosity is in a range of at least about 300 centipoises to about 30,000 centipoises at 25C. in a 2 percent aqueous solution as measured on a Brookfield viscometer and the materials have an alkoxyl D. S. in a range of about 0.7 to about 2.5 and preferably in the range of l.2l .4 and/or a hydroxyalkoxyl M. S. in a range of about 0.1 to about 3.0 and preferably in the range of 0.5-1.0. In this regard, ethylhdroxyethyl celluloses having viscosities within the mentioned range and having an ethoxyl degree of substitution of 1.2-1.4 and a hydroxyethyl M. S. of 0.51 .0 are especially useful in the practice of this invention. However, it is to be noted that acceptable compositions may also be obtained with the use of proteins such as the water-soluble proteins exemplified by egg albumin, hydrolyzed keratins, gluten, zein, soy and cotton seed whipping proteins, as well as microbial proteins such as torula yeast proteins.

In a composition where an added binder is used, the binder may be present in widely varying amounts and there is present at least enough to form a coherent mass with the tobacco and other constituents, should they be employed. As a practical matter, however, about 2 percent to about 30 percent, by weight, based on the total weight of the composition, is employed.

It is to be understood that where a composition containing a tobacco substitute is prepared in accordance with the invention the use of a binder such as those set forth above is optional. Such is also true where a natural tobacco material is to be formulated with the ammonium polyphosphate materials disclosed herein since naturally occurring gums present in the tobacco can be utilized to provide the required binding properties. On the other hand, in either case it may be desirable to use an added binder even with these compositions. It is utilized in the same manner and performs the same function as in a truly reconstituted tobacco product.

In carrying out the practice of the present invention, the compositions may be formulated so that they may be cast into varying shapes such as pipe plugs or fillers, rod-like cigar or cigarette forms or continuous sheets or processed by plastics methods. Moreover, regardless of the particular physical'form, the compositions may be either foamed or unfoamed. Consequently, where foamed compositions are to be made a foaming agent in amounts sufficient to provide a significant increase in volume of about 50 percent to about 300 percent or more based on the original volume of the composition is utilized. A wide variety of foaming agents are suitable. Examples of such foaming agents are carbon dioxide, nitrogen, oxides of nitrogen and air. Moreover, where necessary, suitable foam stabilizers may be optionally employed in minor amounts of about 0.5 percent or less to 10.0 percent or more by weight, based on the total weight of the composition. Suitable stabilizers include polyglycerin stearate, ethylhydroxyethyl cellulose, glycerin monostearate and the like. Air, of course, is a readily available and preferred foaming agent which may simply be introduced into a composition by beating to trap air particles therein before the composition is shaped into its final form.

The compositions of this invention can be prepared by a wide variety of methods. Generally, however, the present compositions are prepared simply by mixing the constituents in the desired proportions, preferably in proportions coming within the ranges set forth hereinabove, at a temperature in a range extending from the freezing point to the decomposition temperature, that is, from about C. to about 100 C. of the mixture and preferably from about C. to about 50 C. and agitating the mixture until a homogeneous composition is obtained. Subsequently, the mass may be converted to final shape as a sheet or other form in any suitable known manner as mentioned before. The process generally comprises mixing tobacco, finely divided tobacco or a tobacco substitute and incorporating the ammonium polyphosphate in the mixture with agitation to provide homogeneity with or without other added ingredients. The mass may them be mixed with water to form a slurry and cast into sheets which are dried to a preselected moisture content which generally ranges from about 2 percent to about 40 percent or handled as is by plastic technology and dried to a product moisture content. In those particular cases where a foamed product is being manufactured, a foaming agent, as well as a form stabilizer which is optional, may be added directly to the adhesive and tobacco or tobacco substitute material after which the composition is shaped into a sheet or some other suitable form. Where air is to be utilized as a foaming agent, it is only necessary to beat, whip or agitate the mixture of adhesive or finely divided tobacco or tobacco substitute until the required amount of air is present in the composition to give it the foamed consistency desired.

Where a composition comprising natural tobacco and the ammonium polyphosphate is being prepared, the constituents are simply mixed together in the form of a slurry and then shaped as desired. On the other hand, it is also possible with such compositions to treat the tobacco with an aqueous dispersion of the ammonium polyphosphate which may be coated on the tobacco in any suitable manner such as by brushing, spraying or other similar procedural steps.

In order to illustrate the present invention more fully, the following examples are set forth. In the Examples all parts and percents are by weight unless otherwise indicated.

EXAMPLE I A tobacco slurry was prepared by adding, with mild agitation, 0.5 parts (dry basis) of a 3.0 percent dispersion of refined sulfite pulp to one part (dry basis) of a 2 percent aqueous dispersion of methyl cellulose which has a viscosity of 15,000 centipoises. The pulp dispersion and the methyl cellulose dispersion were each at about 5 C. before mixing at about C. or less after mild agitation. To this mixture there was added 0.3 parts (dry basis) of a 2 percent solution of ethylhydroxyethyl cellulose having a D. S. of 1.2, an M. S. of 0.5 and a viscosity of 15,000 centipoises. There was also added 8.7 parts of a 20 percent aqueous dispersion of minus 80 mesh Bright tobacco leaf and 0.5 parts (dry basis) of ammonium polyphosphate having an average molecular weight of about 200,000. The completed slurry was mixed for about l5 minutes to produce a substantially uniform mass at approximately 16 C. The slurry was then foamed with air to a density of 0.55 grams per cc. using a Hobert mixer with a wire whip and the resultant foamed slurry was cast on a moving stainless steel belt at a thickness so that the tobacco slurry film after drying weight about six grams per square foot. The foamed tobacco sheet produced had a thickness of about 25 mils. The sheet so produced was shredded and used as cigarette filler and compared with a control made in thesame manner but which did not contain the ammonium polyphosphate. Comparative smoking properties of the control and the cigarettes containing the ammonium polyphosphate are shown in the following table.

The above data clearly indicate that ammonium polyphosphate is a burn retardant and increases the number of puffs per cigarette and the number of puffs per gram tobacco consumed in contrast to cigarettes which do not contain the ammonium polyphosphate. In addition, the cigarettes made from the composition containing the ammonium polyphosphate had a gray cohesive ash and good burn characteristics with no flowering of the ash in contrast to the control which burned to a black ash which was not cohesive and which further exhibited uneven burn characteristics and flowering of the ash directly behind the burning zone.

EXAMPLE II The process of Example I was repeated except that monobasic and dibasic ammonium phosphate were employed in place of the ammonium polyphosphate. The results obtained in comparison to a control containing no phosphate are contained in the following table:

Number Approximate percent of pufis to Number pufis ammonium phos- 25 milligram/tobacco Sample No. pirate (dry basis) meter consumed 1 None-control. 5 10. J 5.02 dibasic 6 14. 4 3.. 0.6 dibasic S 17.0 4 5.02 nion0hasie 8 17.0 5. 9.6 monobasic. 9 19. 3 6. 5.02 monobasic 6 13. 6 7. 3.1 monobasie. 5 12. 0 8 1.05 monobasic. 6 13. 1 9- 5.07 monobasic. 7 15. 9 1O 1.06 monobasic 56 11.8

The ash in all of the samples was very black and not cohesive. A number of the samples exhibited uneven bum characteristics, as well as flowering of the ash directily behind the burning zone. 'In contrast the ammonium polyphosphate, Example 1, provides good burn characteristics and no flowering of the ash, as well as resulting in a cohesive ash which is gray in color rather than black.

EXAMPLE III A 6 percent solids dispersion of refined Burley stem pulp was prepared to a Shopper-Riegler freeness of minus 300 cubic centimeters using the stern pulp preparative procedure described by Light and Osborne in US. Pat. No. 3,464,422. To six parts (dry basis) of this tobacco stem pulp there was added, with agitation, four parts (dry basis) of a 20 percent dispersion of minus 120 mesh Wisconsin leaf dust, 0.25 parts of a 2 percent aqueous dispersion of ethylhydroxyethyl cellulose with an ethoxyl D. S. of 1.6, a hydroxyethyl M. S. of 1.2 and a viscosity of 300 centipoises. There was also added to the mixture 1.0 parts (dry basis) of ammonium polyphosphate having an average molecular weight of about 20,000. The mixture was agitated until a uniform dispersion was obtained with care being taken to prevent the slurry temperature from rising above 20 C. The resultant tobacco slurry was then foamed to a density of 0.60 grams per cubic centimeter and cast and dried in a sheet form as in Example I. The sheet so produced was shredded and used as cigar filler and compared with a control made in the same manner but which did not contain the ammonium polyphosphate. Upon combustion, the cigars made from the composition containing the ammonium polyphosphate had a gray, cohesive ash and exhibited good burn characteristics with no flowering of the ash. In contrast, the control cigars burned to a black ash which was not cohesive and which exhibited uneven burn characteristics and flowering of the ash directly behind the burning zone.

EXAMPLE IV An aqueous dispersion containing 2 percent of ammonium polyphosphate having an average molecular weight of 1,500,000 was mixed with minus 80 mesh Bright tobacco leaf to provide a proportion on a dry basis of 10 percent of the polyphosphate in comparison to the tobacco. To the resulting dispersion was added 5 percent (dry basis) of a 2 percent aqueous dispersion of methylcellulose with a Brookfield viscosity of 15,000 cps at this concentration. The resulting dispersion was cast and dried in sheet form, and the product chopped or shredded for use as pipe tobacco or cigarette filler. The pipe plugs and cigarettes had excellent burning qualities and produced a cohesive gray ash with no evidence of flowering behind the burning zone. In contrast, pipe plugs and cigarettes made from the same tobacco which had not been treated with ammonium polyphosphate produced a black ash with poor cohesive qualities and the cigarettes, upon combustion, exhibited definite flowering of the ash behind the burning zone.

EXAMPLE V Example IV was repeated except that an ammonium polyphosphate was employed which had an average molecular weight of about 500,000. Moreover, in place of the tobacco, a corn silk substitute was employed. The results obtained upon combustion were similar to those obtained in Example IV, in both the product containing the polyphosphate and the product which did not contain this material.

EXAMPLE Vl Example I was once more repeated except that a partially oxidized cellulose was employed in the place of natural occurring tobacco. In this Example, as with the others, the product containing the ammonium polyphosphate showed excellent combustion characteristics providing a cohesive gray ash with no flowering behind the buming zone, in contrast to a non-cohesive black ash and flowering behind the burning zone on cigarettes which did not contain the ammonium polyphosphate.

The compositions of this invention present many advantages. For example, they may be easily prepared with materials which are readily available through commercial channels. Moreover, they may be manufactured by relatively simple manufacturing methods on equipment presently employed in the tobacco industry. Furthermore, compositions in accordance with the invention provide definite improvements in burning characteristics and the products of combustion exhibit'definite improvements of an aesthetic nature, as well as from a practical standpoint since the appearance of the ash is greatly improved, and, furthermore, the ash produced is cohesive. Furthermore, flowering of the products upon combustion is eliminated. This is, of course, advantageous in retaining the shape of the smoking article while it is being consumed. Therefore, less danger of the spread of hot ashes which results in consequent decrease in the risk of fire is realized.

Numerous other advantages of this invention will be readily apparent to those skilled in the art. Moreover, numerous modifications of this invention may be made without departing from the spirit and scope thereof and it is to be understood that the invention is not to be limited, except as defined in the appended claims.

What is claimed is:

1. A smoking composition comprising between about 60-95 percent tobacco, an ammonium polyphosphate additive having an average molecular weight of 20,000 to about 1,500,000, and a binder selected from the group consisting of natural or synthetic gums, the polyphosphate constituting between about 2 percent to about 10 percent weight the composition.

2. The smoking composition of claim 1 wherein the said composition constitutes a foamed product. 

2. The smoking composition of claim 1 wherein the said composition constitutes a foamed product. 